Solid Composite Material for Delivering Viable Cells into Skin Tissues via Detachable Dissolvable Microneedles.

Delivering cells to desired locations in the body is needed for disease treatments, tissue repairs, and various scientific investigations such as animal models for drug development. Here, we report the solid composite material that when embedded with viable cells, can temporarily keep cells alive. Using the material, we also show the fabrication of detachable dissolvable microneedles (DMNs) that can instantly deliver viable cells into skin tissue. B16-F10-murine-melanoma (B16-F10) and human-embryonic-kidney-293T (HEK293T) cells embedded in the solid matrix of the hyaluronic/polyvinylpyrolidone/maltose (HA/PVP/maltose) mixture show 50.6 ± 12.0 and 71.0 ± 5.96% survivals, respectively, when kept at 4 °C for 24 h. Detachable DMNs made of the HA/PVP/maltose mixture and loaded with B16-F10-cells were constructed, and the obtained DMN patches could detach the cell-loaded needles into the skin within 1 min of patch application. In vivo intradermal tumorgrafting mice with the DMNs containing 800 cells of B16-F10 developed tumors 10 times bigger in volume than tumors induced by hypodermic needle injection of suspension containing 100,000 cells. We anticipate this work to be a starting point for viable cell encapsulation in the solid matrix and viable cell delivery via DMNs.